The following code generates the error "Stack Overflow: try tail recursion?"
The code reads in bibliographic data using OAI-PMH and updates a database for each chunk of data. With OAI-PMH, only part of the data is available for each request, so the server returns a resumption token if there are more data available.
The xquery function making the queries is implemented recursively preceded by a database update request (see the last two lines) for each call. Is it db:add() that causes the stack overflow? The recursion cannot be placed further towards the end!
declare %updating function local:getResumption($token) { if (empty($token)) then () else let $http-request := http:send-request($http-option, $URL || $token) let $result := if ($http-request instance of node()) then $http-request else <http-err>{$http-request}</http-err>
let $resume := $result//oai:resumptionToken/text() return ( db:add($database,element chunk {$result//oai:metadata}, $path) , local:getResumption($resume) ) };
Best, Lars